One-pot fabrication of magnetic biochar by FeCl3-activation of lotus seedpod and its catalytic activity towards degradation of Orange G

An advanced magnetic biochar (MBC) was facilely prepared via one-pot FeCl3-activation of lotus seedpod. Simultaneous carbonization, activation, and magnetization formed magnetic Fe3O4 nanoparticles and nanowires over the biochar base. The specific surface area (S-BET) and the total pore volume (V-total) of MBC were 349 m(2) g(-1) and 0.31 cm(3) g(-1), which were 2.0-fold and 3.9-fold higher than those of biochar, respectively. In addition, the saturation magnetization of MBC reached 6.94 emu g(-1), facilitating its magnetic separation and recovery. In heterogeneous Fenton-like catalytic oxidation, 0.40 g l(-1) MBC decolorized 100% Orange G and reduced 58% COD by 350 ppm H2O2 within 120 min. The degradation kinetics were calculated with different MBC samples and reactions followed pseudo-first-order kinetics with the highest rate constant of 0.034 min(-1). Moreover, the catalytic activity dropped by only 6.4% after four reuse cycles, with negligible iron leaching of 1.31-1.44 mg l(-1). Based on these results, MBC could be a low-cost, highly effective, and relatively stable catalyst for treating Orange G in wastewater.